The present disclosure relates to a comb-based spectroscopy.
Fourier transform spectroscopy (FTS or FTIR) has long been a workhorse system for research and industry. Recent advances in spectroscopy using dual frequency combs offer an interesting new approach to FTS. Frequency combs are stabilized pulsed lasers that produce a comb of well-defined frequency lines (hence the name frequency comb) in the frequency domain, equivalent to many CW lasers. They can also be considered in the time domain where they emit a train of optical pulses with a well-defined carrier frequency and repetition rate. Frequency comb sources are attractive for spectroscopy since they can be used, in principle, to combine the benefits of heterodyne laser spectroscopy with broad spectral coverage for high resolution, broadband measurements of samples. In a dual-comb spectroscopy approach, one comb probes a sample and a second comb acts as a local oscillator to read out the response. This dual-comb spectroscopy approach can be viewed as a form of infrared time-domain spectroscopy (TDS) analogous to THz TDS, or as a massively parallel multi-heterodyne laser spectrometer. It can be used to perform spectroscopy on a passive sample or on an active CW source.